Stabilization of aqueous suspensions or colloids containing water-insoluble particles is a problem that is encountered in many industries including agriculture, food and beverage, petroleum, and paint industries. Sedimentation and phase separation of aqueous suspensions or colloids containing water-insoluble particles during storage and transportation may require the additional process of re-homogenization at the point of use. Re-homogenization may be costly, difficult to perform, or impractical.
Carrageenan, an extract of red seaweed, is widely recognized as an effective stabilizer and texturizer and its use in the food and beverage industry has been increasing over many years. The stabilizing effects of carrageenan are well known in the art. Carrageenan forms a thixotropic system and when properly utilized can indefinitely stabilize aqueous suspensions or colloids containing water-insoluble particles. However, carrageenan does not possess its full stabilizing functionality unless completely dissolved and does not readily dissolve unless processed using the proper heating, stirring, and cooling procedures. Furthermore in drink applications, carrageenan must be present in a relatively narrow range of concentration in order to stabilize the suspension or colloid. Too much carrageenan results in a gelled, pudding-like solution that is not acceptable for drink applications. Too little and the water-insoluble particles settle to form sediment. Traditionally, beverage-stabilizing grades of carrageenans have been extracted from wild-harvested seaweeds. However, there is a limit to the supply of wild harvested seaweeds. As a result, there is a need for effective alternative stabilizer systems for beverages.
The polysaccharide xanthan gum is a hydrocolloid that is manufactured using a natural fermentation process involving the microorganism Xanthomonas campestris. Xanthan gum is commonly used as an additive in the food industry as a hydrophilic colloid to thicken and stabilize emulsions, foams, and suspensions. In processed foods, xanthan gum provides stability and improves or modifies textural qualities, pouring characteristics and cling. Xanthan gum is unique in its rheology in that while it does not form gels, it exhibits pseudo-plastic flow with very high viscosity at low shear rates and low viscosity at high shear rates. In general, the concentration of xanthan gum required for effective stabilization is related to the particle size and density of the water-insoluble particles. In many cases, the concentration required to effectively stabilize the solution may result in unwanted results including excessive viscosity. Therefore, it may not be possible to prevent sedimentation and phase separation while maintaining the desired flow characteristics of drink applications. Finally, even at high concentration, xanthan gum may not be able to eliminate all sedimentation. In the event that sedimentation does occur, the increased viscosity due to the presence of xanthan gum makes re-suspension of sediment particles significantly more difficult.
Konjac mannan is a glucomannan extracted from the root of the Konjac plant (Amorphophallal konjac). Konjac mannan has a high capacity for water absorption and can swell to about 200 times its original volume. Konjac mannan is unique in that it has the highest viscosity of any known dietary fiber. Due to its high viscosity and capacity for water absorption, konjac mannan has been proposed for use in emulsions to increase stability and as a thickening agent. See U.S. Pat. No. 4,582,714. Konjac mannan is commercially available in several different manufacturers. Konjac mannan has been added to juice drinks in a concentration of approximately 0.01% by weight of the mixture to increase the viscosity of the drink. See U.S. Pat. No. 7,037,539. Konjac mannan has also been suggested as an additive for providing a creamy mouth feel to drinks. See U.S. Pat. No. 6,180,159. However, konjac mannan solutions are difficult to prepare. Even at low concentration and relatively high temperatures, konjac mannan requires rigorous agitation to fully dissolve. Furthermore, the viscosity of konjac mannan gels are not shelf stable as the viscosity decreases by a significant amount within 5 to 10 hours at room temperature. See U.S. Pat. No. 8,003,152.
Xanthan gum and glucomannan, such as konjac mannan, synergistically interact to form strong, self-supporting, elastic, and thermally reversible gels. Several factors may affect gel strength of a gel resulting from the combination of xanthan gum and glucomannan. For example, gel strength may be enhanced by heating the mixture of xanthan gum and glucomannan above the coil-helix transition of xanthan gum. The ionic strength of the solvent in which xanthan gum and glucomannan are dissolved has an inverse relationship with gel strength. Therefore, increasing the salt concentration or lowering the pH results in weaker gels. The degree of acetyl substitution is also inversely related to gel strength (i.e. decreasing acetylation increases gel strength). See U.S. Patent Application Publication US 2012/0021112 A1. However, the previously described gels resulting from xanthan gum and glucomannan do not have the flow characteristics required for use in drink applications. Xanthan gum is also known to synergistically interact with galactomannans to provide greater viscosity than provided by the use of either element alone. Xanthan gum and other viscous soluble fibers also interact with certain proteins wherein the protein decreases the viscosity of the soluble fiber. For example, proteins include wheat protein, egg protein, collagen protein, whey protein, casein protein, gluten, pea protein, soy protein, silk protein, and combinations thereof, lower the viscosity of konjac mannan, xanthan gum, guar gum, beta glucan, and pectin compositions. See U.S. Patent Application Publication US 2006/0099324.
To conclude, there is still a need for a drink stabilizing composition that minimizes phase separation and sedimentation while also providing creamy mouth feel and smooth flow characteristics desired in drink applications.